Greetings to all,
I started responding to each reply off line. I am getting so many
responses, and most are similar, so I am responding through the reflector.
The idea of increased IMD is something I have not considered. I
would certainly think that PIN's would be much better, in this respect, as
they are much cleaner mixers than PN diodes. But, how much cleaner is
cleaner?
The idea of proper forward biasing is something that I have
considered, and I certainly agree that switching diodes must be turned on
"HARD" (Yes, I got it too), and had to avoid rectification during switching.
Both the HeathKit and Ameritron boards use 12 volts for forward biasing.
Any comments would be appreciated.
I have to comment on Carl's thread. I have not been able to get
through to them lately, either. My bone with them is that their Quality
Control is awful, almost non-existent. Since I have started messing with
QSK, I have bought two QSK-5, stand alone units, from them. One was dead
right out of the box and the other failed within the first week of
operation. The one that was dead out of the box was caused by a short of on
the board from mounting too close together. This one took out two PIN
diodes an two of the hi voltage switchers. The other one was simply cold
solder joints. I see this regularly on boards send in for me to repair.
Often, just repositioning components, and/or reheating solder joints fixes
the problem. I do not think that new products should come out of the
factory this way. Antenna tuners should not be sold with a rating of 1500
watts, when in actuality, their coils get so hot with 1500 watts that the
solder melts and flows away, leaving an open circuit because there was no
physical connection made before soldering.
Now, on the other side of the issue, I certainly do recognize the
good that they do for the Amateur Radio Community, at large. I just wish
they had a little better quality control.
73 de Lon, K5JV
1110 Golden Bear Ln.
Kingwood, TX 77339
281-358-4207
281-358-4234 FAX
281-795-1335 CELL
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